Coordinated fluoride in rhenium(I) carbonyl complexes

Abstract

Bromide abstraction from the complexes Re(CO)₃L₂Br (where L = SbPh₃ and L₂ = bpy, dpe, tmen)* by AgF₂H gives the corresponding fluoro compounds Re(CO)₃L₂F. Mass spectra and structural data show that the fluoride in these complexes is coordinated to the metal. The structures of Re(CO)₃(tmen)F and [Re(CO)₃(tmen)F]₂H.HOBF₃ are reported here. Crystals of Re(CO)₃(tmen)F are monoclinic, space group P2₁/c, with a 8.202(2), b 13.115(9), c 12.048(4) Å and β 102 24(3)º. A full-matrix least-squares refinement by using the absorption corrected data gave a conventional R value of 0.041. [Re(CO)₃(tmen)F]₂H.HOBF₃ also crystallizes in the space group P2₁/c. The lattice parameters are: a 17.495(2), b 10.772(2), c 15.447(1) Å and β ( 101.409(8)º. The final R value of a blocked least-squares calculation converged at 0.061. In these two complexes the simple Re-F distance is 2.040(4) Å, in Re(CO)₃(tmen)F. The Re-F distance is increased to 2.236(10)Å, as a result of hydrogen bonding between the fluoride and HOBF₃ in the latter compound.